Mourinho's men remain top of the pile, but they could be overtaken by both Manchester City and Liverpool this weekend.
"I know mathematically it is still possible to win the league but we now depend too much on other results," he told the club's official website after today's match.
"We could have scored in the first half and had chances to equalise but it's fair to say Palace deserved it.
"Our opponent beat us clearly on mentality. They were aggressive and committed and all played to their potential."
Next up for the Blues is a trip to Paris Saint-Germain in the quarter-finals of the Champions League on Wednesday night.